REUTRERS, JERUSALEM- Palestinian security forces loyal to Hamas and Fatah have both carried out serious human rights abuses over the past year, including arbitrary arrests and torture, according to a report on the bitter power struggle.

Human Rights Watch, in the report released on Wednesday, cited a pattern of politically motivated arrests, mock executions and severe beatings in detention centers run by Hamas Islamists in the Gaza Strip and President Mahmoud Abbas's secular Fatah faction in the West Bank.

It faulted the United States and other donors, who have bankrolled Abbas's Palestinian Authority and Fatah-dominated security forces, for "not paying adequate attention to the systematic abuses by those forces".

Hamas, which receives support from Iran and other Islamist allies, routed Fatah in the Gaza Strip a year ago, seizing control of the coastal enclave after months of fighting that killed hundreds. Abbas and his Fatah-led security forces still hold sway in the Israeli-occupied West Bank.

Internal tensions spiked again after a bomb blast killed five Hamas militants and a girl in the Gaza Strip on Friday. Hundreds of Hamas and Fatah supporters have since been detained in both territories in tit-for-tat crackdowns.

The Hamas-run Interior Ministry in the Gaza Strip declined to comment on the Human Rights Watch report, but the group says those who commit abuses are punished.

Senior Fatah official Hussein al-Sheikh said Fatah forces in the West Bank were acting within the law and accused Hamas of using "savage and brutal practices".

Most abuse cases documented by Human Rights Watch in the West Bank involved Abbas's General Intelligence and Preventive Security services, which Abbas has granted broad law enforcement powers to protect his West Bank-based government.

SERIOUS ABUSES

Joe Stork, deputy Middle East and North Africa director at Human Rights Watch, said Western powers should make support conditional on Abbas's security forces "stopping torture and other serious abuses".

Washington helps train and equip Abbas's National Security forces and Presidential Guard, while the European Union provides training to Abbas's civil police. The funding sources for General Intelligence and Preventive Security remain unclear.

Stork said money and training should not go to forces that ignored Palestinian or international human rights law, adding that Hamas's backers should likewise make aid conditional on reforms "to avoid complicity with human rights violations".

According to Human Rights Watch, masked Fatah security men in the West Bank have arrested hundreds of Hamas members and supporters without warrants.

The report said Fatah forces often tortured detainees during interrogation, apparently resulting in one death. Torture methods included mock executions, kicks and punches, and beatings with sticks, plastic pipes and hoses, it said.

The most common form of torture was forcing detainees to stay in "stress" positions, a practice known in Arabic as shabah, which causes intense pain and sometimes internal injury but leaves no physical mark, Human Rights Watch said.

Hamas forces in Gaza committed many of the same abuses, including arbitrary detentions accompanied by severe beatings and, in two cases, multiple gunshots at close range to the legs, Human Rights Watch said. In at least three cases, individuals died in custody, apparently from torture, the report said.

Human Rights Watch said Hamas and Fatah have both largely failed to hold accountable security men implicated in abuses.

Hamas officials in Gaza told Human Rights Watch that they had punished or disciplined more than 700 police officers for rights abuses, but provided few details.

West Bank officials told the group they had disciplined or punished officers for abuses, but provided no cases or numbers.